Sliding attachment for boat propeller



June 25, 1963 1.. A. HEINTZELMAN SLIDING ATTACHMENT FOR BOAT PROPELLERFiled Aug. lb. 1960 Leo A. He/h/ze/man INVENTOR.

BY WW 5M United States Patent 3,095,043 SLIDING ATTACHMENT FOR BDATPROPELLER Leo A. Heintzelman, Grmdville, Mich. (4990 Burlingame, Wyoming9, Mich.) Filed Aug. 10, 1960, Ser. No. 48,680 2 Claims. (Cl. 170-16011)The present invention generally relates to an attachment for boatpropellers and more particularly to uch an attachment that will slideradially outwardly to increase the surface area of the propeller bladethus maintaining the operation of the propeller at its maximumefiiciency.

It is well known that engines used in propelling boats and especiallysmall boats produce their maximum horsepower at a relatively highrotational speed. Inasmuch as the resistance to rotation of thepropeller for the boat is the same at low rotational speeds as it is athigh rotational speeds, the engine quite frequently will not reachoptimum operating speeds until after an extended period of time.Therefore, the present invention incorporates a structure which willenable the resistance to rotation of the propeller to be relatively lowin the initial stages of rotation of the propeller and until thepropeller reaches a predetermined speed at which time the attachment ofthe present invention will be rendered efiective by centrifugal forcethus increasing the efiective diameter and surface area of the blades ofthe propeller thereby increasing the resistance .to rotation and ofcourse propelling the boat in the desired manner. The extending of theattachment is no accomplished until such time as the boat propeller hasreached a predetermined speed inasmuch as centrifugal force is reliedupon to operate the attachment.

Still another important object of the present invention is to provide anattachment for boat propellers which is in the form of a sliding elementspring biased radially inwardly and movable outwardly in response tocentrifugal force and including means for guiding the movement of theattachment in relation to the propeller blades.

Still another important object of the present invention is to provide apropeller attachment which will not materially increase the thickness ofthe propeller blades thus enabling the propeller blades to operate insubstantially their normal eflicient manner.

Still another feature of the present invention is to provide anattachment for a boat propeller which is simple in construction, easy touse, effective for its particular purposes and generally inexpensive tomanufacture.

These together with other objects and advantages which will becomesubsequently apparent reside in the details of construction andoperation as more fully thereafter described and claimed, referencebeing had to the accompanying drawing forming a part hereof, whereinlike numerals refer to like parts throughout, and in which:

FIGURE 1 is an end elevational view of a boat propeller employing theattachment of the present invention thereon;

FIGURE 2 is a detailed sectional view taken substantially upon a planepassing along section line 22 of FIGURE 1 illustrating the details ofthe attachment;

FIGURE 3 is a detailed sectional view taken substantially upon a planepassing along section line 33 of FIGURE 2 illustrating further detailsof the spring mechanism for retaining the attachment in place; and

FIGURE 4 is an exploded group fragmental perspective view of thecomponents of the attachment and the manner in which the components areassembled.

Referring now specifically to the drawings, the numeral generallydesignates a propeller on which the attachment of the present inventionis mounted and the attachment is generally designated by the numeral 12.The propeller 10 is of substantially conventional construction andincludes a centrally disposed hub 14 for receiving the end 3,095,043Patented June 25, 1963 of a propeller shaft in the usual manner.Extending outwardly from the hub 14 is a pair of propeller blades 16 ofidentical construction and the propeller blades are disposed at adesired angle and are of a particular size dependent upon the particulartype of motor or engine which will drive the propeller. The constructionof the hub and the orientation of the blades 16 is conventional and eachblade 16 is provided with a generally curved outer edge 18 Adjacent theouter edge 18 of each 'blade 16 is the attachment 12 which is in theform of substantially an arcuate plate 20 having a rounded outer edge 22generally conforming to the edge 18. The end edges of the plate 20 arerounded as indicated by the numeral 24 and the inner edge thereof isprovided with a concave curvature 26 thereon.

The plate 20 is adapted to move inwardly and outwardly in relation tothe blade with one end of the plate 20 generally moving along a radiusextending from the center of the hub 14 and the other end of the plate20 moving in parallel relation thereto.

For mounting the plate 20 slidably on the blade 16, there is provided apair of pins 26 and 28 extending through apertures 30 in the blade 16and retained in position by cotter pins 32 or the like. The other end ofthe pins '26 and 28 are headed as indicated by the numeral 34.

The pins 26 and 28 extend through an elongated generally rectangularslot 36 in the plate 20* and the pins are in alignment with each otherin the direction of sliding movement of the plate 20.

Overlying the slot or enlarged opening 36 and forming a closure thereforis a retaining plate 38. The pins 26 and 28 also extend through theretaining plate 3% and retains the plate 38 against the outer surface ofthe sliding plate 20 for forming a closure for the opening or slot 36 inthe sliding plate 20. Thus, the plate 20 is capable of sliding betweenthe blade 16 and the retaining plate 38 and the plate 20 is retained inposition by the pins 26 and 28 extending through the opening 36 whichlimits the sliding movement of the plate 30.

Means is provided for spring biasing the sliding plate 20 inwardly andthis mean includes a flattened spiral coil compression spring 40 havingthe end edges or portions 42 of the innermost loop received in notches44 in the side edges of the opening 36. The other end of the spring 40is provided with a hook 46 for attachment to the outermost pin 26. Thus,as the plate 20 moves outwardly, it will carry the lowermost convolutionof the spring 40 with it thus compressing the spring 40 whereby thespring 40 will normally urge the sliding plate 20* back towards the hub14. The hook 46 is securely fixed to the pin 26 and will cooperate withthe spring 40 to exert force on the plate 20 for retaining it inretracted position.

Normally, the extensible plates or blades 20 are in retracted positionwith the outer edge 22 coincident with the outer edge 18 of the blade16. This condition will be maintained during initial low speed rotationof the propeller thus enabling the engine which propels the propeller toreach an optimum operating speed. As this optimum speed is approached,the centrifugal force exerted on the plates 20 due to the rotation ofspeed of the propeller will overcome the tension of the springs 40 andthus compress the springs 40 and the plate 20 will be moved outwardlyinto the dotted line position illustrated in FIGURES l and 2 thusincreasing the efiective surface area of the blades 16 for increasingthe resistance to rotation of the propeller and, of course, increasingthe thurst on the boat. However, this does not occur until the enginehas reached the optimum operating speed thus enabling the engine toobtain its optimum operating speed quicker than with a conventionalpropeller.

The plate 20 is also provided with an inwardly extending flange 21 thatengages the opposite surface of the blade 16 in relation to the plate 20thereby forming a guide for movement of the plate 20 during movementthereof. The flange 21 also serves to stabilize the extensible plate 20'and retain it in position when in the retracted position.

The foregoing is considered as illustrative only of the principles ofthe invention. Further, since numerous modifications and changes willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact construction and operation shown anddescribed, and accordingly, all suitable modifications and equivalentsmay be resorted to, falling within the scope of the invention asclaimed.

What is claimed as new is as follows:

1. In combination with a boat propeller having a plurality of generallyradially extending blades, an attachment comprising an elongatedextensible plate for each blade of the propeller, each of said platesoverlying and extending across one face of the outer end portion of thecorresponding blade and having a curved outer longitudinal edge portiongenerally conforming to the plan outline of the outer edge portion ofthe corresponding blade, means at each of the opposite ends of eachplate slidably mounting that end on and exteriorly of the correspondingblade by means of a pin and slot connection for movement generallyradially of the corresponding blade and including resilient meansconnected between portions of said blade and the corresponding plateyieldably urging said plate toward a radially inwardly displacedposition relative to the corresponding blade when the propeller isrotated at slow speed and enabling the plate to move radially outwardlywhen the propeller is rotated at higher speeds, said pin and slotconnections on each extension plate including a pair of enlargedopenings formed in and disposed adjacent the opposite ends of theplates, retaining means projecting laterally from the one face of eachof said blades extending through each opening and anchored to thecorresponding propeller blade, a retainer member on the outer ends ofeach of said anchor means and slidably engaging the correspondingextensible plate thus slidably retaining the extension plate inposition, said resilient means interconnecting the anchor means and theextension plates for biasing each of the extension plates radiallyinwardly of the corresponding blade, said means urging the extensionplate inwardly of the propeller blade including a flattened spiral coilspring disposed in each opening and having one end anchored to theextension plate and the other end anchored rigidly in relation to thepropeller blade thereby resiliently biasing the extension plate inwardlyin relation to the propeller blade.

'2. The combination of claim 1 wherein the innermost convolution of thecoil spring is provided with laterally extending members, the edges ofthe openings in the extension plate having notches therein receiving theedges of the lowermost convolutions of the spring thereby anchoring thespring to the extension plate.

References Cited in the file of this patent UNITED STATES PATENTS1,569,473 Garcia Jan. 12, 1926 2,021,470 Upson Nov. 9, 1935 2,885,012Heintzelman May 5, 1959 2,992,686 Heintzelrnan et al July 18, 1961FOREIGN PATENTS 325,296 Germany Sept. 11, 1920 a 425,914 Great BritainMar. 25, 1935

1. IN COMBINATION WITH A BOAT PROPELLER HAVING A PLURALITY OF GENERALLYRADIALLY EXTENDING BLADES, AN ATTACHMENT COMPRISING AN ELONGATEDEXTENSIBLE PLATE FOR EACH BLADE OF THE PROPELLER, EACH OF SAID PLATESOVERLYING AND EXTENDING ACROSS ONE FACE OF THE OUTER END PORTION OF THECORRESPONDING BLADE AND HAVING A CURVED OUTER LONGITUDINAL EDGE PORTIONGENERALLY CONFORMING TO THE PLAN OUTLINE OF THE OUTER EDGE PORTION OFTHE CORRESPONDING BLADE, MEANS AT EACH OF THE OPPOSITE ENDS OF EACHPLATE SLIDABLY MOUNTING THAT END ON AND EXTERIORLY OF THE CORRESPONDINGBLADE BY MEANS OF A PIN AND SLOT CONNECTION FOR MOVEMENT GENERALLYRADIALLY OF THE CORRESPONDING BLADE AND INCLUDING RESILIENT MEANSCONNECTED BETWEEN PORTIONS OF SAID BLADE AND THE CORRESPONDING PLATEYIELDABLY URGING SAID PLATE TOWARD A RADIALLY INWARDLY DISPLACEDPOSITION RELATIVE TO THE CORRESPONDING BLADE WHEN THE PROPELLER ISROTATED AT SLOW SPEED AND ENABLING THE PLATE TO MOVE RADIALLY OUTWARDLYWHEN THE PROPELLER IS ROTATED AT HIGHER SPEEDS, SAID PIN AND SLOTCONNECTIONS ON EACH EXTENSION PLATE INCLUDING A PAIR OF ENLARGEDOPENINGS FORMED IN AND DISPOSED ADJACENT THE OPPOSITE ENDS OF THEPLATES, RETAINING MEANS PROJECTING LATERALLY FROM THE ONE FACE OF EACHOF SAID